1. Technical Field
The present invention relates to a detection device capable of detecting a change in capacitance, and specifically relates to a detection device and a display device, which are capable of detecting an external proximity object based on a change in capacitance.
2. Description of the Related Art
In recent years, a detection device capable of detecting an external proximity object, or a so-called touch panel, has attracted attention. A touch panel is mounted on or integrated with a display device such as a liquid crystal display (LCD) device and used in a display device with a touch detection function. In the display device with the touch detection function, various kinds of button images are displayed on the display device, so that information can be input through the touch panel instead of normal mechanical buttons. The display device with the touch detection function including the touch panel does not need an input device such as a keyboard, a mouse, and a keypad, and has been increasingly used in portable information terminals such as mobile phones in addition to computers.
As a technology of a touch detection device, there are several technologies such as an optical type, a resistive type, and a capacitive type. A capacitive touch detection device has a comparatively simple structure in a portable terminal or the like and can realize low power consumption. Further, in a detection device capable of detecting an external proximity object, low resistance of a detection electrode has been required to make the device thinner, have a large screen, or achieve a high resolution. For the detection electrode, a transparent conductive oxide such as an indium tin oxide (ITO) is used as a material of a transparent electrode. In order to lower the resistance of the detection electrode, it is effective to use a conductive material such as a metallic material. However, when the conductive material such as the metallic material is used, the detection electrode may be corroded. A detection device including a detection electrode covered with a protective layer is disclosed in Japanese Patent Application Laid-open Publication No. 2015-176573.
When the detection electrode has a mesh-like pattern, the detection electrode has low resistance. However, when the detection electrode is coupled to a coupling wire that extends in a different direction from an extending direction of the mesh-like pattern of the detection electrode, the coupling wire blocks the protective layer from spreading, and thus the protective layer does not fill a region in the detection electrode and an air bubble remains in the protective layer, which may lead to nonuniformity of light distribution on a plane, or deterioration in reliability.
For the foregoing reasons, there is a need for a detection device and a display device that suppress an air bubble in the protective layer.